This paper presents methodologies and technologies that are exploited to design and implement the mobile haptic grasper (MHG), i.e. an integrated system consisting of a mobile robot and two grounded haptic devices (HD) fixed on it. This system features two-point contact kinaesthetic interactions while guaranteeing full user’s locomotion in large virtual environment. The workspace of haptic interaction is indefinitely extended, and this is extremely relevant for applications such as virtual grasping, where the global workspace is typically reduced with respect to those of the single-point contact devices. Regarding software architecture, we present the Haptik Library, an open source library developed at the University of Siena which allows to uniformly access HD, that has been used to implement the MHG software
Abstract. Potential applications of online virtual worlds are attracting the interest of many researchers around the world. One and perhaps the most famous example of such systems is Linden Lab's Second Life. Last year, sources for its client application have been released under the GPL license, allowing anyone to extend it building a modified client. This work presents an effort to explore the possibilities that haptic technologies can offer to multiuser online virtual worlds, to provide users with an easier, more interactive and immersive experience. A haptic-enabled version of the Second Life Client, supporting major haptic devices, is proposed. Two haptic-based input modes have been added which help visually impaired people to navigate and explore the simulated 3D environment by exploiting force feedback capabilities of these devices.
Abstract-In this paper we present a new method for realtime interactive haptic and graphic rendering of complex objects locally deformed by multiple contacts. Core algorithms have been designed to be executable also on videoboard's GPU, thus taking advantage of parallel matrix and vector computational power. Although complex physical simulation has been simplified to run on GPUs, results are characterized by high visio-tactile realism perceived by users. Graphical rendering algorithms can be easily added to pre-existing vertex shaders/programs. The proposed method makes use of common triangular meshes, thus making the method a good choice when adding haptic feedback to existing graphical applications.
Abstract. The apparent mass of haptic device end-effector depends on its position inside the workspace. This paper presents a recursive algorithm to detect effective direction of gravity force, and to automatically estimate the apparent mass of the end-effector when placed at the vertices of a cubic grid contained into the device workspace. Then an on-line technique is proposed to actively compensate gravity, exploiting trilinear interpolation to compute an estimate of end-effector apparent mass in any position of the workspace. Experiments have been performed with three different haptic devices, and results shown that the apparent mass of the end-effector is compensated almost homogeneously with respect to its position in the workspace.
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